How about installing a "Holiday/Illness"-mode and the possibility of loosing (tiny) amounts of gold for not using this mode when you have to be absent for a longer period of time?
I have found that in almost all situations, the same result can be achieved by rewarding the behavior you want to incentivize rather than penalizing which turns people off.
In this case, I support the idea of rewarding active players (which is the same as penalizing inactive players). Thus, we have the daily login / veteran bonus which rewards gold every day that you visit the site, which is really the same as penalizing the people that don't.
I guess you could have the Holiday/Illness mode give you the veteran bonus without requiring daily login, but I don't think that's very intuitive and people would probably abuse it.
Maybe you are right. Maybe. I have to admit that I have not been thinking it to a proper end. But this was about erasing inactive player-accounts more then penalizing inactive players. And it was about the possibility to lose gold...for the gold sticks to our accounts and is rather useless, at least when you have bought everything and are not into 'buying' leadership awards